1. Field of the Invention
This invention relates to solid and semi-solid state electrolyte composites which contain an electrically insulating ribbon or sheet of expanded or perforated plastic which is coated with an ion conductive solid or semi-solid state matrix, and solidified by an alkali metal triflate salt, or an alkaline earth metal triflate salt and a radiation curable polymer.
2. Description of the Prior Art
In the prior art various polymers have been used as components of the electrolytes of solid state alkali metal, and alkaline earth metal batteries, and various other kinds of electrochemical devices.
Among the problems associated with the use of these polymers in electrolytes is that they have inherent relatively low ionic conductivity, and also may react with the alkali metals used, such as lithium, or other metallic anodes, to form a non-conductive boundary layer, which prevents the free flow of ions and hinders rechargeability.
Various solutions have been proposed such as described in the U.S. Patents to Hope et al., U.S. Pat. No. 5,102,752; Schwabet et al., U.S. Pat. No. 4,792,504; Ballard et al., U.S. Pat. No. 4,822,701; Bauer et al., U.S. Pat. No. 4,654,279; Lee et al., U.S. Pat. No. 4,830,939; and Lee et al., U.S. Pat. No. 4,990,413.
The prior art polymer containing electrolytes also have exhibited poor adherence to the electrodes, are not flexible and do not possess sufficient mechanical strength to prevent shorting under pressure, or punching through of dendrites and consequent shorting of the device.
While electrically insulating fibrous structures in solid ribbon or mesh form are used in composite electrolytes, and are satisfactory for their intended purpose, the fibrous non-woven fabrics are usually of 1.5 mils or more thickness, are bulky, and also cost more than are optimal. None of the prior art patents suggests, discloses or describes the composite electrolytes described herein.
The composite electrolytes of the invention do not suffer from prior art problems and provide many positive advantages.